Nat/Pat - Planet GRT-101 User Manual

PLANET Technology GRT-101 User's Manual

3.7.3 NAT/PAT

NAT can be used to share an Internet connection, to reduce the requirement
for publicly assigned IP addresses, to expand an existing network without
affecting existing IP based account schemes, and to hide an internal network
schema from public networks.
It is often used in the situation where only one IP address could be assigned
for the network, such as a PPP connection to an local ISP, e.g., when your
local ISP uses protocols of "PPPoA" or "PPPoE" over the ATM VC, you get a
dynamic public IP at the WAN port from your local ISP. All requests originating
from the LAN (private network) have their source IP addresses replaced with
the public IP address. Only one IP address is visible from the public network.
To setup this GRT-101 working for the above example, enter:
admin# setup lan 1 attrib Virtual
Also, make sure to delete all entries in the NAT/PAT IP pools by the following
commands:
admin# setup ip_share nat virtual delete <1~5>
admin# setup ip_share nat global delete <1~5>
admin# setup ip_share nat fixed delete <1~128>
admin# setup ip_share pat clear <1~10>
Note: The maximum number of hosts on the LAN (private network) is limited to be of 253 in dynamic NAT.
To save your changes, enter:
admin# write
In some cases, the number of externally visible IP addresses is greater than
one and less than the host number being hidden behind GRT-101. You could
configure GRT-101 such that it acts as follows. Each time a request is made
from a host on the LAN, which is included in virtual IP pool, e.g., pool 3:
192.168.0.2~192.168.0.25. GRT-101 chooses an external IP address already
configured in the corresponding global IP pool 3 (e.g., 69.210.1.2~69.210.1.7,
which is assigned from your local ISP) that is currently unused, and then
performs the translation. This type of situation is only possible when the
number of hosts having concurrent requests to the external network is equal to
or less than the number of external IP addresses on GRT-101. To setup
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